Norman Foster and Margaret Atwood are to star in a collaboration between two of Edinburgh's largest festivals as part of a new initiative to expand the reach and audience of the city's international book festival.

In a joint project with the Edinburgh film festival this August – the first on this scale attempted by two of the city's 12 annual festivals – Foster and Atwood will be amongst a number of prominent guests exploring the different techniques film-makers and writers use for biographies.

The events will be staged at the Filmhouse cinema complex, where this year's film festival is now taking place, as part of plans by the new director of the city's international book festival, Nick Barley, to develop an event based for nearly 30 years in a "tented city" in the gardens of Charlotte Square in the city's Georgian New Town.

Barley unveiled his first programme today, which features 750 authors. It includes a rare public appearance by Doonesbury cartoonist Garry Trudeau in conversation with Guardian cartoonist Steve Bell, three Nobel prize winners, including Joseph Stiglitz, the poet Seamus Heaney, the hairdresser Vidal Sassoon and an opening debate on Jesus between the atheist author Philip Pullman and former bishop of Oxford Richard Harries.

The former chancellor Alistair Darling is to give his first speech on politics and the economy since Labour lost the general election, while seven leading South African poets and writers prevented from attending this year's London book fair by the Icelandic ash cloud will fly in for a series of events.

The Australian writer Christos Tsiolkas, author of a controversial novel on race and class, The Slap, and the first Edinburgh Unesco City of Literature writer in residence, will be speak on the opening day. The festival closes with a discussion on "the new world order" and geo-politics – a theme of this year's festival – with the Portuguese Nobel laureate Jos&eacute; Saramago.

Foster, one of Britain's most famous architects and designer of Wembley stadium, the Reichstag, the British Museum's "great court" and one of the towers at "ground zero" in New York, is appearing at the UK launch of his biography How much does your building weigh Mr Foster? It has been made into a feature-length film by the Art Commissioners consultancy.

Atwood will appear at the joint book and film festival event by satellite link from Canada, to talk about her recent novel The Year of the Flood. Other major names for this mini-festival are to be announced next month.

There had been speculation that Barley would move events outside Charlotte Square, or even relocate it entirely. In an interview with the Guardian, Barley said he was committed to remaining there. "It provides an oasis of calm in the chaos and bustle and joy of the rest of the festivals, and I'm not interested in changing that," he said. "Having said that, I'm perfectly happy doing things elsewhere and collaborating with other festivals."

He suggested the festival could even eventually colonise surrounding roads on Charlotte Square with marquees, closing two sides to traffic, if the city council agreed.

Barley said his revamped programme featured five "innovations", among them the idea of inviting four guest "selectors", including Bell, Ruth Padel, great-great granddaughter of Charles Darwin, and Don Paterson, the poet, to invite writers and cartoonists to take part in different strands of the festival.

The four worked on the themes of poetry, political satire and cartoonists, the future of fiction, and the relations between parents and their children. The latter theme, co-curated by Padel, will culminate in a debate between Fay Weldon and Fatima Bhutto, niece of the assassinated Pakistani leader Benazir Bhutto and daughter of Murtaza Bhutto, who was shot dead by police, about the tragic and violent loss of a parent.

Barley said this model would be followed at future festivals. A novice at directing festivals and given only seven months since his appointment last October to build this year's programme, Barley denied the guest curators were there to help lighten his workload. His predecessor, Catherine Lockerbie, credited with building Edinburgh's reputation as the world's largest book festival, stepped down last year after being seriously ill with stress and exhaustion.

"Far from being a lightening of the load, it has been an increasing of the workload but a joyful one," he said. "The key to it has not so much been a lightening of the load but about acknowledging that choosing 750 events from one person's head is a particular thing, and I'm interested in a variety of perspectives on the world."

Other strands include week-long themes such as the US's role in the world. This strand will feature 45 American authors such as Trudeau, Lionel Shriver, Joyce Carol Oates and David Vann, chaired by the BBC journalist Allan Little. There will also be a focus on first books by new writers, a "first book award" chosen by the festival audience, and a series of free evening events hosted by as yet undisclosed writers, musicians and cartoonists.

Barley said he had no plans for an overnight revolution in the way the festival was staged. But he said there was a pressing need to innovate, partly to see off competition from other events. In 1983, there were only four literature festivals in the UK. There are now nearly 400. "I do envisage many, many new innovations," he said. "We're very friendly with all the other festivals in the UK and abroad, but we're very aware we have to keep innovating to stay ahead."